Police in Lafayette, La., are intensifying their search for a young woman who has been missing for four days.

Michaela "Mickey" Shunick was last seen riding a bike home from her friend's house about 2 a.m. Saturday, according to police. The Federal Bureau of Investigation and the Lousiana State Police have joined the search, along with volunteers scouring the area where she was last seen.

Friends and family held a candle light vigil Tuesday night, and announced a reward of $20,000 for tips leading to her whereabouts. Searches by K-9 units, police and volunteers haven't turned up any hints about what happened, but her family remains hopeful.

Instead of celebrating her brother's graduation Saturday and her own 22nd birthday Tuesday, her family and friends were hitting the pavement hanging fliers and searching for clues along the route they believe she last traveled.

Her parents say Mickey is an avid cyclist, so for her to be riding her bike at that hour was not unusual. They do say that their daughter would never disappear for days on end like this.

Police say the search is particularly difficult because the area they are searching is so large.

"It's a very wide scope for us to look at," Cpl. Paul Mouton said to KATC. "We're canvassing and checking a lot of different businesses for video evidence."

The senior anthropology major at the University of Louisiana at Lafayette is 5 feet, 1 inch tall and 115 pounds. She was last seen wearing a pastel multi-colored striped shirt, light-wash skinny jeans and gray shoes. She also reportedly always carries a can of mace with her when she rides her bike.

Her family says they can't think of any reason anybody might want to harm Shunick, and her father said although he's grateful for the search efforts, he wishes the search had started earlier.

"None of the video cameras got checked over the weekend because the managers weren't in and waited two days to check the video cameras," he told Lafayette newspaper The Advertiser. "If somebody has abducted her and taken her on the Interstate or something, they got a two-day head start."

Still, those who know Mickey hope raising awareness about her disappearance will help them find her.

"Every volunteer has been amazing. The outpouring from the community has been more than I could have imagined," Shunick's friend Ashley Says told KATC. "People that don't even know Mickey, who don't even know her family have been coming to me and saying they will do anything to help."

Mickey's parents say that she always carried mace to protect herself on her bike. Right now they are hoping that somehow, she makes it home.

"Nothing has turned up so we still have hope -- hopefully everything will be all right," her father Tom Shunick said.